Punch construction



Dec. 25, 1951 J. A. SMITH PUNCH CONSTRUCTION Filed April 28, 1950 IN ENTJOR. %aca5 a mz% Patented Dec. 25. 1951 UNITED sures rcur or FITCE 2,580,366 PUNCH CONSTRUCTION J acob, A; Smith, Chicago, Il1.,"a;ssignor of one-half to. .ClaudeiA..-Benjamin, Chicago, .Ill.

' [ApplicationrApril'28, 1950, SerialNo..158,"807

This invention relates to "punch constructions 'and, more particularly, to "a construction for "punching accurately located non-circular holes .in sheet material.

the punch be accurately mounted so that the hole will be properly positioned-and in the case of non-circularpunches the angular position is also critical. It is one of the objects of the present invention to provide a punch construction which accomplishes 'th'ese several objectives.

.Another object is toprovi'de *a punch construction in which "the-punch is" located by a relatively 'short'locating bore at the outer end of a mounting quill. Preferably the locating bore is noncircular in section and receives a correspondingly shaped locating section on the punch, the remainder of the bore and punch being of cylindlical sections.

St ll another ob ect is to provide a punch construction in which the ouill is formed with three al gned bores, the outermost of wh ch is the locating bore and receives a re atively short punch, having a cylindrical body fitting into the intermed ate bore, a relatively short cylindr cal head in the lar est bore. and a locating section in the locating bore, and in wh ch the punch is held in the quill by a back-up pin in the largest bore.

The above and other obiects and advantages of the invention will be more readily a parent from the fo lowing descript on when read in connection with the accompanying drawing, in wh ch:

Figure 1 is a side elevation with parts in sect on showing a punch construction embodying the invention;

Fi ure 2 is an assembled view of the punch construction with the quill in section; and

Figure 3 is a disassembled view of the punch construction.

The punch as shown in Figure 1 may be used with a conventional press having a punch pad l0 movable toward and away from a base or die supporting plate ll. One or more punches may be held on the pad ID by a holding plate l2 detachably secured to the pad and formed with cylindrical openings 1 3 to receive quill bodies. The openings l3 terminate at the upper end of the holding plate in enlarged sockets I4, which are preferably non-circular in section, to receive similarly-"shapedheads on the quill. 'In:.the con- 'struction shown, the quill "is providedwith'a'head I5 which is generally cylindrical "but which is formed with a flat spot Hi'to fit into a similarly shaped socket in the holding pl'atefthereby 'to fix the angular'pos'ition of the quill accurately and easily.

The punch construction of the invention includes a quill having ahead as described above and a body i'l cylindrical on its "outersur'face. The quill is providedwith three aligned bores, includinga bore [8 of maximum diameter-extending from the upper orhead end of the quill throughoutthe maior portion of the quill length. The bore 18 connects to an intermediate bore i9 which is cylindrical and which'is connected to the bore {ISby an internal shoulder 2|. A'tthe outer endof the quill is a short locating'bore 22, which is preferably =non circularin section. In the construction shown, the bore 22 is square, although this exact shape is not critical. In forming a quill as shown, the cylindrical bores I8 and I9 may be drilled in any desired manner to be co-axial. and since these bores extend throu h substantially the full length of the quill the locat g bore 22 can be ma e very short. The bore 22 can be broached or otherwise formed to a non-circular section, but since it is extremely short this o eration can be performed inexpensively and with the necessary degree of accuracy.

The quill is adapted to receive a relatively short punch, having a main cylindrical body 23 of a diameter and len th to fit in the intermediate bore l9. Preferably the body 23 is slightly shorter than the bore I9 so that a sli ht clearance will be left between the body and the punch locating section. At its upper end the body is formed with a cylindrical head 24 of a size to fit into the bore l8 and which is connected to the punch body by an annular shoulder to fit against the internal shoulder 2| in the quill. At its lower end the punch body is formed with a reduced locating section 25 of the same sha e as the locating bore 22 to be received in the locating bore. Beyond the locating section 25 is a reduced punch tip 26 to project beyond the end of the quill when the parts are assembled. The punch is held against displacement in the quill by a cylindrical back-up pin 21 which fits in the bore i8 and rests against the punch pad when the punch is assembled in a press.

With this construction, when the punch is used, the impact force produced in the punch itself when it pierces the metal is taken by the enlarged head 24 of the punch. Since the punch is relatively short this impact force is held down to a relatively low value so that punch breakage beneath the head will be minimized. Furthermore, formation of the punch with several different diameters increasing to a maximum at the head tends to distribute the stresses more evenly throughout the punch body, further to assist in reducing breakage. The back-up pin [8, being free to shift in the quill, is subjected to no breaking forces.

Also, with the present construction, it will be seen that the locating section 25 of the punch, an cooperation with the locating bore 22 of the quill, performs the major part of the function of locating the punch accurately. Since these parts are relatively short, they can be formed with an extremely high degree of accuracy without making the cost of the assembly excessive. When the locating section and the locating bore are non-circular as shown, they additionally, in conjunction with the fiat spot 16 on the quill head, provide an accurate angular positioning of the punch tip. This is extremely important in cases where a non-circular punch tip 26 is employed.

In the event a punch must be removed for sharpening or replacement the holding plate 12 can be detached from the punch pad and the quill caneasily be removed therefrom. With the quill removed the back-up pin and punch can be taken out of the quill and a new punch or the same punch resharpened and easily reinserted in the quill. It will be observed that it is impossible in this operation to reassemble the parts in an incorrect position and that the entire operation can be performed very simply and quickly. Furthermore, since the punch is a relativelysmall unit, it is inexpensive and can be replaced much more cheaply than an integral part construction.

While one embodiment of the invention has been shown and described in detail, it will be understood that this is illustrative only and is not to be taken as a definition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

1. A punch construction comprising a tubular quill having three aligned bores of progressively decreasing area joined by internal shoulders, the smallest of said bores being at the outer end of the quill, and being non-circular in section, a punch having a relatively short head fitting m the largest bore, a body fitting in the intermediate bore, a locating section of the same cross section as and fitting into the smallest bore, and a tip of non-circular section projecting from the quill, the head being joined to the body by an external shoulder fitting against one of the internal shoulders, and a back up pin fitting in the largest bore and seating against the head.

2. The construction of claim 1 in which the quill includes a generally cylindrical head at the end opposite the smallest bore with a locating portion thereon deviating from thegeneral cylindrical outline of the head.

JACOB A. SMITH.

REFERENCES CITED 'The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name l Date 80,349 Higgins July 28, 1868 1,507,783 Luce Sept. 9, 1924 2,299,534 De Lorme Oct. 20, 1942 2,364,011 Wales Nov. 28, 1944 

